Water Level Measurement Sensor

[YoYo]

All this talk of water has got me to thinking about something I've wanted to do for awhile....

And that is measure the actual level of water in a small cistern outside my home. Right now, I have a float switch that tells me when the level reaches a certain point, but I'd really like to know how many feet of water are in it at any given time.

I've looked at a few non-contact options, like the Sonix-40, and a few others, but they're all over $650, which seems a bit expensive to me.

Anyone got a lead on something perhaps lower tech that would do the job?

[Stuart]

Hi,
you could possibly use a float with a round magnet with a hole big enough to fit over a small pvc tube and have reed relays every 1/2 ft or so. The float would ride on the tube up or down with the water level. Then when a relay makes contact you would keep that reading as the last setting and always be within 1/2 foot of the true level.
Stuart

[YoYo]

Hi Stuart,

I guess I'd have to find some reed switches that were submersible...

I did think about buying some GRI water detection switches and using them on a pipe. Same idea, but no float to worry about.

I'll have to measure to see just how much distance I'd want to measure, but I'm thinking it would be around 5 feet or so...

Thanks,

[YoYo]

I was even thinking about a marine depth finder. These can be had for less than $80 complete. I could put it on a float in the cistern. But I have no idea how to get the depth reading out of one into something an HA input could use...

[BraveSirRobbin]

I was even thinking about a marine depth finder. These can be had for less than $80 complete. I could put it on a float in the cistern. But I have no idea how to get the depth reading out of one into something an HA input could use...

http://www.cocoontech.com/index.php?showtopic=2827

To further prove this point I incorporated this methodology into a garage door monitor that tracks my garage door's position to within a couple of inches (the bottom of the door is from ground level).

http://www.cocoontech.com/index.php?showtopic=3184

[langenet]

I get it... it seems like great solution. However, humity and damp conditions may cause an issue if the pot is within close proximity of the water/liquid. As you mentioned, you could incorporate other elaborate mechanical means to keep things farther away from the water source... I've been thinking about this as well. Just haven't got to it on the list of things to do...

Robert

[Stuart]

You could try one of these...
http://www.livorsi.com/catalog/waterproof.htm

Stuart

[smoothtlk]

Think automotive gas tank fuel level sensor. buy it off the shelf from an autoparts store, or a junkyard.

[BraveSirRobbin]

...humity and damp conditions may cause an issue if the pot is within close proximity of the water/liquid.

The pot I used in my Garage Door How-To has a humidity military specification rating of "MIL-STD-202, Method 103, Condition B". If I found the correct information; to have this certification a component must undergo exposure to a relative humidity of 90 to 95 percent at a temperature of 40 degrees C for a time period of 96 hours.

[BraveSirRobbin]

Think automotive gas tank fuel level sensor. buy it off the shelf from an autoparts store, or a junkyard.

Not sure if you would have enough "throw" for a four ft depth.

[YoYo]

Not sure if you would have enough "throw" for a four ft depth.

Nonetheless, a very innovative approach to the problem! I don't really have enough access to inside the cistern to mount something like this though.

I have also looked at the automotive level senders as well, but it would appear that most would not cover a 4' depth range...

Most of the submersible pressure transducers seem to run over $300 as well.

Stuart, the link you gave shows something that would work up to 72" if necessary, but it looks like the range would still only be a foot. Looks like it's a variable resistance on the probe which one could use in a circuit as BSR described. I don't see any with a conventional HA interface like voltage, current loop, or serial...

Thanks for all of the suggestions!

[smoothtlk]

If you can connect a water T to the bottom and take a pipe up the side of the top with a vent at the top, then you could put conductivity sensors along the length of the pipe from top to bottom. The more you regularily space, the more resolution you will get. I betcha there would be a 1 wire device that might help that you could daisy chain wire.

[YoYo]

If you can connect a water T to the bottom and take a pipe up the side of the top with a vent at the top, then you could put conductivity sensors along the length of the pipe from top to bottom. The more you regularily space, the more resolution you will get. I betcha there would be a 1 wire device that might help that you could daisy chain wire.

I thought of something like this, but was concerned about two things; first, to get the resolution I would want would require using a lot of inputs, or another controller in the middle to sort it out. Second, I'm not sure how long it takes the typical water sensor to reset once it's out of the water, especially in a damp environment. I was hoping I could monitor when it was being pumped, which would probably require sensors that could "reset" fairly quickly.

After some more digging, I did find a company from Austrailia that is making an ultrasonic device that is a lot more reasonable ~$200, than some of the others. It's by Hexamite and is called the HX6 series. Even has a serial interface, and wireless capabilities. And, since it's ultrasonic in nature, doesn't actually have to get wet. I think I'm going to check it out....

[mfisher]

YoYo, a few questions...

What is the depth of the cistern?
What maximum height of water do you want to measure?
Does the water ever freeze?

[YoYo]

What is the depth of the cistern?
What maximum height of water do you want to measure?
Does the water ever freeze?

I believe it's about 10 feet deep give or take.
The max height of the water would probably be 5-6 feet.
Shouldn't freeze, it's underground, but would get quite chilly.

FYI, also looked at some stuff from K-Tek and Omron, and Omega.
Looks to me like they all have stuff that would do the job just fine. But, either they're too expensive for me, or it's very hard to find a place to actually buy them. There is also Aquaguage for about $190 which wouldn't be a bad approach either, just don't want batteries or any maintenance.